Volvo Penta Backfires underload

tylerdale101

Seaman Apprentice
Joined
Jun 8, 2017
Messages
30
Hi all,

I am trying to figure out fuel injection. I have had quite a bit experience with Mercruiser carburated models but new to both fuel injection and Volvo Penta. My engines model number is 50FAPNCA (Ford 5.0). My boat had a clear rod knock but ran so I pulled it out and replaced it with a remanufactured 5.0 engine bored .030 over. I set timing as stated on engine to 5 degrees BTDC with spout removed. The problem with the boat is that it has a hard start meaning take around 10 seconds to fire up and once it does it wont go above around 2000 RPM without back firing out the intake and not going any further when under load. With out load when the boat is in neutral the engine it does run good and can reach WOT. The spark plugs were new but are now carbon fouled with dry black soot. I replaced distributor cap and rotor. I tested fuel pressure at the rail and came back 39 psi key on 31psi engine running. Any help or advice would be appreciated!

Thanks, Tyler
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,969
the backfire under load is a lean sneeze or your timing is way out of wack. your fuel pressure is low
 

tylerdale101

Seaman Apprentice
Joined
Jun 8, 2017
Messages
30
the backfire under load is a lean sneeze or your timing is way out of wack. your fuel pressure is low
any advice on why it would be low? It ran before engine swap. does it need any change or reprograming since cylinders were bored out?
 
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